New Layered Compounds with Honeycomb Ordering: Li3Ni2BiO6, Li3NiM′BiO6 (M′ = Mg, Cu, Zn), and the Delafossite Ag3Ni2BiO6

The new layered compound Li3Ni2BiO6 has been prepared by a solid-state reaction. It crystallizes in the monoclinic C2/m space group; its lamellar structure is characterized by a honeycomb ordering between Ni2+ and Bi5+ within the slabs, while Li+ ions occupy octahedral sites in the interslab space. Stacking defects weakly alter the XRD pattern. By substitution of half of the nickel ions, the new phases Li3NiM'BiO6 (M' = Mg, Cu, Zn) isostructural with Li3Ni2BiO6 have been synthesized under similar conditions. All these compounds demonstrate paramagnetic behavior at high temperature, and Li3Ni2BiO6 exhibits an antiferromagnetic ordering at 5.5 K. By topotactic molten salt ionic exchange, the new delafossite compound Ag3Ni2BiO6 has been also obtained and characterized.